[PATCH 06/27] ext4: refactor ext4_collapse_range()

Zhang Yi
2024-10-22T03:13:01Z

From: Zhang Yi <yi.zhang@huawei.com>

Simplify ext4_collapse_range() and align its code style with that of
ext4_zero_range() and ext4_punch_hole(). Refactor it by: a) renaming
variables, b) removing redundant input parameter checks and moving
the remaining checks under i_rwsem in preparation for future
refactoring, and c) renaming the three stale error tags.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
fs/ext4/extents.c | 103 +++++++++++++++++++++-------------------------
1 file changed, 48 insertions(+), 55 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f843342e5164..a4e95f3b5f09 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -5295,43 +5295,36 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
struct inode *inode = file_inode(file);
struct super_block *sb = inode->i_sb;
struct address_space *mapping = inode->i_mapping;
- ext4_lblk_t punch_start, punch_stop;
+ loff_t end = offset + len;
+ ext4_lblk_t start_lblk, end_lblk;
handle_t *handle;
unsigned int credits;
- loff_t new_size, ioffset;
+ loff_t start, new_size;
int ret;

- /*
- * We need to test this early because xfstests assumes that a
- * collapse range of (0, 1) will return EOPNOTSUPP if the file
- * system does not support collapse range.
- */
- if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
- return -EOPNOTSUPP;
+ trace_ext4_collapse_range(inode, offset, len);

- /* Collapse range works only on fs cluster size aligned regions. */
- if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb)))
- return -EINVAL;
+ inode_lock(inode);

- trace_ext4_collapse_range(inode, offset, len);
+ /* Currently just for extent based files */
+ if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }

- punch_start = offset >> EXT4_BLOCK_SIZE_BITS(sb);
- punch_stop = (offset + len) >> EXT4_BLOCK_SIZE_BITS(sb);
+ /* Collapse range works only on fs cluster size aligned regions. */
+ if (!IS_ALIGNED(offset | len, EXT4_CLUSTER_SIZE(sb))) {
+ ret = -EINVAL;
+ goto out;
+ }

- inode_lock(inode);
/*
* There is no need to overlap collapse range with EOF, in which case
* it is effectively a truncate operation
*/
- if (offset + len >= inode->i_size) {
+ if (end >= inode->i_size) {
ret = -EINVAL;
- goto out_mutex;
- }
-
- /* Currently just for extent based files */
- if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
- ret = -EOPNOTSUPP;
- goto out_mutex;
+ goto out;
}

/* Wait for existing dio to complete */
@@ -5339,7 +5332,7 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)

ret = file_modified(file);
if (ret)
- goto out_mutex;
+ goto out;

/*
* Prevent page faults from reinstantiating pages we have released from
@@ -5349,55 +5342,52 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)

ret = ext4_break_layouts(inode);
if (ret)
- goto out_mmap;
+ goto out_invalidate_lock;

/*
+ * Write tail of the last page before removed range and data that
+ * will be shifted since they will get removed from the page cache
+ * below. We are also protected from pages becoming dirty by
+ * i_rwsem and invalidate_lock.
* Need to round down offset to be aligned with page size boundary
* for page size > block size.
*/
- ioffset = round_down(offset, PAGE_SIZE);
- /*
- * Write tail of the last page before removed range since it will get
- * removed from the page cache below.
- */
- ret = filemap_write_and_wait_range(mapping, ioffset, offset);
- if (ret)
- goto out_mmap;
- /*
- * Write data that will be shifted to preserve them when discarding
- * page cache below. We are also protected from pages becoming dirty
- * by i_rwsem and invalidate_lock.
- */
- ret = filemap_write_and_wait_range(mapping, offset + len,
- LLONG_MAX);
+ start = round_down(offset, PAGE_SIZE);
+ ret = filemap_write_and_wait_range(mapping, start, offset);
+ if (!ret)
+ ret = filemap_write_and_wait_range(mapping, end, LLONG_MAX);
if (ret)
- goto out_mmap;
- truncate_pagecache(inode, ioffset);
+ goto out_invalidate_lock;
+
+ truncate_pagecache(inode, start);

credits = ext4_writepage_trans_blocks(inode);
handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
if (IS_ERR(handle)) {
ret = PTR_ERR(handle);
- goto out_mmap;
+ goto out_invalidate_lock;
}
ext4_fc_mark_ineligible(sb, EXT4_FC_REASON_FALLOC_RANGE, handle);

+ start_lblk = offset >> inode->i_blkbits;
+ end_lblk = (offset + len) >> inode->i_blkbits;
+
down_write(&EXT4_I(inode)->i_data_sem);
ext4_discard_preallocations(inode);
- ext4_es_remove_extent(inode, punch_start, EXT_MAX_BLOCKS - punch_start);
+ ext4_es_remove_extent(inode, start_lblk, EXT_MAX_BLOCKS - start_lblk);

- ret = ext4_ext_remove_space(inode, punch_start, punch_stop - 1);
+ ret = ext4_ext_remove_space(inode, start_lblk, end_lblk - 1);
if (ret) {
up_write(&EXT4_I(inode)->i_data_sem);
- goto out_stop;
+ goto out_handle;
}
ext4_discard_preallocations(inode);

- ret = ext4_ext_shift_extents(inode, handle, punch_stop,
- punch_stop - punch_start, SHIFT_LEFT);
+ ret = ext4_ext_shift_extents(inode, handle, end_lblk,
+ end_lblk - start_lblk, SHIFT_LEFT);
if (ret) {
up_write(&EXT4_I(inode)->i_data_sem);
- goto out_stop;
+ goto out_handle;
}

new_size = inode->i_size - len;
@@ -5405,16 +5395,19 @@ static int ext4_collapse_range(struct file *file, loff_t offset, loff_t len)
EXT4_I(inode)->i_disksize = new_size;

up_write(&EXT4_I(inode)->i_data_sem);
- if (IS_SYNC(inode))
- ext4_handle_sync(handle);
ret = ext4_mark_inode_dirty(handle, inode);
+ if (ret)
+ goto out_handle;
+
ext4_update_inode_fsync_trans(handle, inode, 1);
+ if (IS_SYNC(inode))
+ ext4_handle_sync(handle);

-out_stop:
+out_handle:
ext4_journal_stop(handle);
-out_mmap:
+out_invalidate_lock:
filemap_invalidate_unlock(mapping);
-out_mutex:
+out:
inode_unlock(inode);
return ret;
}
--
2.46.1